Headspace-micrometer



. H. EICKHOFF AND AND c. A. TuNKs.

HEADSPACE MICROMETER.

APPLICATION FILED JULY 25.

' 7. Y 1,351,721, PAtentedAug. 31,1920.

' 3 SHEETS-SHEET l. l

T. H. EICKHOFF AND ANDC. A. TUNKS.

HEADSPACE MICROMETER. APPLICATION lFILED JULY 25.1917.

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T. H. EICKHFF AND AND C. A. TUNKS. HEADSPACE MICROMETER.

APPLICATIQN FILED JULY 25.1917.

1,351,721, A Patented .31,1920.

3 SHEET 3- y T/Ze-odore Zcislzoff THEODOEE II; EICKHOEE, OE WASHINGTON, 'DISTRICT OE COLUMBIA, .AND cIIAELEs A.

TUNKs, 0E CLEVELAND, OHIO, AssIGNORs, BY DIRECT AND I/IEsNE ASSIGNMENTS,

T0 AUTO-ORDNANCE CORPORATION, OF NEW YORK, N.

y y YORK.

To allee/tom t may concern.'

Be it known that we, Tiinonoini l-I. EIOK- I-ioir and CHARLES A. TUNES, citizens of the United States, residing at llashington, in the District of Columbia, and Cleveland, in the county of Cuyahoga and State of hio, respectively, have invented" certain new and useful lmprovements'in Headspace-Micrometers, of which the following is a'speciiication.

T he invention relates to micrometers, and more particularly is designedl for making interior measurements, and its special, purpose, as herein disclosed, is for gaging the chamber ofl a gun so as to determine -.the h eadspace of such chamber.

The construction is such that this measurement may be conveniently and accurately taken with the bolt mechanism closed,

4so that the dimension of the chamber under actual firing rconditions will be properly del termined.

W e have shown the invention in connection with the oidinary army rifle, but'. it will be understood that its use is not liniited to this or any particular type of gun,

as it is adaptable to any gun using fixed aiiimunitiom;whether it be of thea small arm or ordnance type, in which it is necessary to.` determine fthe headspace ofthe car-A tridge chamber.

In the drawings herewith: .Figure l is a .longitudinal sectional view takenY vertically through so much of va rifle as is necessary to illustrate the use of Vour invention, thel micrometer being shown in the cartridge chamber.

Fig. 2 is a view in side elevation of the micrometer.

of the micrometer shown in Fig. 2.

view looking Ving-'sleevefor thev micrometer .shown in Fig. 5.,

Figi' Sisfafview in endrelevationdof Ythe vsleeve shown in Fig. 5. 4 v

Fig. 9 is an end view of the Vadjusting ringA vormcollar, looking f fromfthe right,

IIEADsPAoE-MICEOMETEE'.

Specification ofi'Letters Patent., P&1;Qnt@d'Aug Application ined July 25, i917. serial No.l isaiasi.v

" provided for right, Fig. vl0. 1

Fig. 3 is a longitudinal sectional view Y., A CORPORATIONr OE NEW Fig. l0 is aviewof so much of the' beam and bodymechanism as will illustrate amodiied A'form in which gripping vmeansare preventing rotation ofthe. body or sleeve.

Fig. 11 is an'end view looking from"the Referring to the drawings by numbers,

llike `numbers indicating'V like-parts in the several' views, g. l0 denotes .aj rifle barrel mounted inthe usual manner, or any suitable mannen-on the `stock (conventionally yshown in Fig. 1?),.said' riiiebarrel` being provided Awith a cartridge chamber 1 ll' of the usual ora-ny selected type, 'the customary j breech closure or-boltv being provided toi function inthe usual manner. lt is customary before giving the' finishing eut to a cartridge chamber 11,'to deter# mine the headspacefof that chamber accurately, in order that when the finaly finishing cut is made, the chambermay be accurately machined to the-proper dimensions and 'uniform headspacev secured for Vthe fixed ammunition used.

The determinationf'rof h'eadspace of the chamber is a matter which requires 'very accurate measurements, and5 being an inside;Y

is a matter whichk has required, sowfar" as wel areadvised,'underlpresent methods considerable time and effort! v The micrometer comprises a beam l2 provided with a `measuring'disk 13 atgone end, a graduatedsectioii 14, a measuringthread soufsection- 15a`nd a cylindrical'iextension '16 i having at its Vextreme end .preferablyl a suared or othertia 17 angular in cross- 1 section. Theigraduated section lll will 'be 95 laid off in any usual or desired mannen'the the present disclosure'. Y

Mounted onsaid beam and inengagement with the measuring thread section l5 thereof, is a measuring` sleeve 18g-one end of graduations beingfconventionally showin' in providedwithgraduations, as 'shown in Fig.

i 2, the graduationsf Oni the beveled end 19 graduations acting in conjunction with the on thesection 14 on thebeam.

The sleeve 18 has anV outer diameter and contour 'of v'substantially the "diameter and contour of theiammunition used in the v which: is'preferably beveled' as at'l9, and

-30 linger-piece 23 by means [2 l A ,l I j 1,351,721

' in the present instance With a shoulder 20 Y corresponding to the shoulder provided on the Yordinary riflecartridge, the said shoulder 2O serving as an abutment Which strikes 5 against the shoulder at the forward endet the cartridge chamber, and the torwarde'nd of the sleeve is in the form of a cylindrical extension 21 Yfitting the bore of the gun. Y

The micrometer as thus described Will be set for ZeroV (0) and inserted inthe cartridge chamber,` its normal length When set for Zero (inthe example shown here)l being 2.497 5. The measurement of that chamber, Whose variation from normal dimensions is 15 tto be determined, Will then bemade by rotating the beam and sleeve relative to each other, so as to lay off onthe graduated scalev such variation, itany exists. Rotation of the beam and sleeve relative to eachother Y 20 vWill be'accomplished by means-of a rod 22 which is introduced from the muzzle ot the barrel lof the gun, ,and hasa complementary engaging end to engage the squared or angulartip 17 on the beam, and While this ens 254v gaging meansr is' a convenient and lsuitable. one, it is to beunderstood Vthat anyxmeans ofengaging the rod and beam to eitect rotation may be adopted. ,The end of the rod 22 is preferably Y provided with a knurled of Which it may bev conveniently turned. Rotation oit lthe rod22 Will, of course, rotate the beam, and

through. the measuring threads thereon which engageL the corresponding Y interior Y threads ofthe sleeve 18, causinga longitu.

dinal Vtravelvoit the beam and sleeve. relative tol each other, vthe frictionalY engagement oi the sleeve 18 with the cartridge chamber beinggsuiiicient toi prevent any rotation of 'the'sleeve. When the beamand sleeve have v been rotated until the shoulder 20 tits snugly the forward Vshouldered end of the cartridge `lchamber, and the disk 13 abutsagainst the'v Y firing bolt, the measurement Will have been v' taken,Y and the, rod 22 civili. then be Withdrawn, atterivhich the micrometerrvvill be Y' removed from the cartridge chamber, and

the-readii'igtaken to show any, variation which must be,-taken1carf ..nt in the finalA l ofiinisliing cut. Y Y t In' that form ofthe-invention'shown in Y.

Figs. 5, 6, 7, 8,y and V9, theconstruction is generally the saine as that just'described,

except that provision is made for correctingv 55, the micrometer if, by-reason of Wear, it is inaccurate. rlhis adjustment and compen-k sation for Wearis secured byproviding the sleeve-T18 withV an `adjustable collar "or ring Y 24, which, as showiiin Fig". 5, is seated in recess inthe sleeve, vand is b elveledat 25, Vas shown, the-bevel of the sleeve carrying the graduations instead ofY forming them, as inV the other type onthe beveled -end of' the sleeve'itself. Thering 24' has a close fric- Y" tional'it inthe recess `of the sleeve so that:

construction, variation due to Wear` can be 175 Y readily compensated for. As'statedabove', j the normal length of the headspace microme eter When the reading is Zero (0) vis,"in this particular disclosure, 2.4197 5, and in order to Y set the headspace micrometer, .i it Wii'l Vbe- 80 placed in a regular micrometer, set for the vrproper dimension, and the beam Will ,thenY be projected until there is a close .iitting of beam and sleeve in the standard micrometer; The ring 24k Will then be rotated-by a 85 f suitable tool to: bring the Zeromark to` proper position and alinement, and any inaccuracies dueto Wear Will have been taken care ot.' Y

While as statedrabove, the rictioniot the 90 body-piece or sleeve of the micrometer isv generally siiicient to prevent rotation oi' that sleeve, when the beam is rotated, to elffeet the adjustmentV of. the movable parts, it maybe desirable to. provide locking means which Will hold the body-'or sleeve .of thev micrometer iixedly so that there is no .possi-4 bility of its vrotatingy asfthe instrument -is manipulatedi f A convenientand eiiicient means of secur-KV 'ofi' spring lingers for' projections 'are pro- Y videdwhich Will take firm locking grip jon 110.v

the inner Wall oi thebore when the micrometer is forcedinto the cartridge chamber. The front of the extension 28Y is beveled asV Y atvSO- so that it may be forced into the bore,

Y readilyr compressing the' spring fiiigersj'as 115` it is'pushed to itsseat.v Y .l c A `Preferably, this spring .linger projection 'f will be internally-bored vor'. chambered asf shovvn,a1id the end Vbeam 31,Which is to' be engaged by the detachable tool, Will'vlie'lzo lwithin the spring linger projectiom'as illus- Y trated in Fig, 10.'- Y

'It 'Wm be' yunderstood thatsuch'.variations4 i Y from the constructions shown as -mechanicalf 5 skill andl eXpedience. may-dictatemaybel'zf" made Without departing from the Vvspiritof the invention. fr i l g Y ,VVe'cla'imrfY s Y Vl.' A headspace micrometer 'forfllmeasur-j ing the length of theiring chamber ina"""130fV movable longitudinally of the beam and adapted to be placed in the firing chamber,

the sleeve and the beam having measuring faces respectively adaptedto engage the for-v' ward and rearward ends of the firing chamber when the firing chamber is closed, and means adapted to extend through the barrel ofthe firearm for moving the sleeve and beam longitudinally of each other when the firing chamber is closed. y

2. A headspaceinicrometer for measuring the distance between the forward end of the firing chamber of a firearm and the forward end of the breech closure when closed comprising a beam and a sleeve threaded on the beam to move longitudinally thereof, they beam and sleeve having measuring sur faces facing` in opposite directions alongthe beam which faces are adapted to engage said ends of the firing chamber and breech closure respectively, and said beam having a portion extending into the barrel of the firearm by means of which the beam may be rotated from the muzzle end of the barrel after the breech closure has been closed to bring said surfaces into engagement with said ends.

3. A lieadspace micrometer for measuringA the length of the firing chamber of a firearm when the breech closure is in closed position comprising two parts adapted to be placed in the firing chamber, the two parts being relatively adjustable longitudinally of the firing chamber and having surfaces facing in opposite directions which surfaces are Y adapted to engage the opposite-ends of the firing chamber, and a third part adapted to be inserted through the barrel of the firearm into engagement with one of said parts Yto effect relative adjustment of said 'first two parts longitudinally of the firing chamber. Y

e. A hcadspace micrometer for measuring the distance from the forward tapered end of a firing chamber to the forward Vend of,- the breech closure vwhen closed comprisingV a beam adapted to be placed in the firingA chamber and a sleevegsurrounding said beam, the beam and sleeve being/longitudinally movable relative to each otherrand ,having registering micrometer calibrations, the rear end of the beam being flat to butt against said end of the` breech closure and the forward end of the sleeve being tapered te lit'said tapered end of the firing chamber,

5. A headspace micrometer for measuring'- the length of the firing chamber in a firen arm comprising a beam adapted to be placed in the ring chamber, and a sleeve threaded on the beam and adapted tobe placed in the firing chamber, said sleeve having substantially thel contour of the firing chamber and the beam and the sleeve having measuringV facesy adapted toy engage the forward and rearward ends of the firing chamber whenthe hring chamber is closed, and means adapted to extend through the barrel of the firearm for rotating'the beam and sleeve relatively to each other to bring said faces into engagement with said ends.

6; A device for measuring the internal dimension of a chamber which is closed except for an opening in one side comprising a beam adapted to extend longitudinally into said opening, a sleeve threaded on said Y beam, said beam and sleeve having nieasuring faces directed away from each other lengthwise of said beam which are adapted to engage the oppositesides of said chainber, said beam being rotatable by means of the portion thereof extending outwardly intoY saidL opening, and said sleeve having yielding friction means adapted to engage the wall of said chamber for preventing rotation thereof with said beam.

7. A device for measuring thefdistance Y between the forward end of the firing chamber of the firearm and the forward end of the breech closure whenV closed comprising l a beam and sleeve threaded on the beam to vmove longitudinally thereof, the beam and sleeve having measuring surfaces facing in opposite ldirections along the beam which are adapted tovengage said'ends of the firing chamber and 'breech closure respectively, means for rotating said beam while the breech closure is closed to bring said surfaces into engagement with Vsaid ends, and said sleeve having'a portion extendinginto the barrel of theifirearm with a snugfit tov prevent the sleeve from:rotatingwith'thev beam.

set our hands. A, Y y

THEODORE H. EICKHOFF. CHARLES A.

In testimony whereof, we have hereuntov 

